Servo-motor for brakes



' June 24, 1930. T ET AL SERVO MOTOR FOR BRAKES Filed Oct. 6, 1927 INVENTORS. 49a, W4.

A TTORNE Y.

Patented June 24, 1930 UNITED STATES PATENT OFFICE SERVO-MOTOR FOR BRAKES Application filed October 6, 1927. Serial No. 224,307.

The. present invention relates to servomotors for the brakes of automotive vehicles, particularly such vehicles as are propelled by internal combustion engines.

Among the objects of the invention is to provide assistance to the operator in applying brakes and in holding them when applied.

Another object is means supplied with motive power from the engine of the vehicle to aid in or to supply the power for applying the brakes.

Other objects will readily occur to those skilled in the art upon reference to the foli lowing description and drawing in which Fig. l is a longitudinal section through the servo-motor; and

Fig. 2 is an elevation from the right of Fig. 1 but on a smaller scale.

In the drawings, the device is shown as comprising a two part metal casing of which one part 1 is somewhat smaller than the other part 2.

The casing is divided into two compartments by a flexible diaphragm 3, the edges of which are clamped between the flanged edges of the 21 The diaphragm 3 is made of a suitable flexible air-tight material and is reinforced by means of an annular concentrically located plate 4 somewhat smaller in diameter than the casing.

Secured to plate 4 on the opposite side of the diaphragm 3 is a spider 8 and to the center of the spider is secured a rod 5 extending from casing part 1 through an axial opening 5 provided with an internal flange 5 It-is preferred also to'provide spider 8 with a central internally threaded boss 8 into which rod 5 screws. This boss 8 and flange 5 provide means to which may be secured as by screws 17 acollapsible sleeve 8 for the purpose of rendering the compartment in this end of the casing air-tight.

The spider 8 is also provided in its under side with a valve seat 8 cooperating with a valve 10 and the seat cavity is connected to the insideof sleeve 8 boss 8 by a passage 18 in casing parts by means of bolts.

Spider 8 is preferably secured to plate 4 by bolts 9, whose threaded ends pass through the plate 4, diaphragm 3 and spider 8 and these elements are fixed on the bolts by nuts 19 and 19, leaving the unthrcaded portion of the bolts to serve as guides for the elements in the compartment in casing part 2.

Mounted loosely on bolts 9 on the opposite side of the diaphragm 3 from spider 8 is a second spider 7 whose movement on the bolts is limited by the bolt heads and other nuts 9. This spider? is also provided with a central internally threaded boss 7 for the reception of the threaded end of a rod (5 extending from casing 2 through an axial opening 6 provided with an inwardly extending flange 6 This flange 6 and boss 7 furnish means for securing around rod 6 as by screws 13 and 23 a second collapsible sleeve 12 serving to close opening 6* and render this end of the casing air-tight.

Spider 7 carries on its underside a small yoke 15 secured to the center of the spider by means of a screw 15*, which yoke embraces and is adapted to move with spider a nipple 11 centrally fixed in diaphragm 3 and held in place by a nut 16. This nipple is provided with a central passage furnishing the sole communication between the compartments, while one end of the nipple forms a seat for a valve 14 adapted to close the passage.

Valve 14 and valve 10 are fixed together by providing one with a stem that screws into the other, thus fixing their relative position and-the valves are provided with a spring 22 tending to seat both.

Further casing part 2 is provided with a nipple 24 by means of which a conduitmav open and the pressure in the two compart- The operation of the device is as follows Assuming the parts in the position shown in Fig. 1 and with a suitable suction pump such as the motor connected with nipple 24, the pressure on both sides of diaphragm is equal as the valve 14 is open and the valve 10 closed. \Vhen the brakes are to' I be applied, the rod 6 is drawn to the left by means of the brake pedal and thereby moves s ider 7 along bolts 9 until stopped by the heads. In the mean time, yoke 15 has moved the nipple 11 to close valve 14 and then open valve 10. As soon as valve 10 has been opened, outside air rushes into the casing 1 throu hopening 5' around rod 5 and passage 18, estroying theequilibrium and causing the diaphragm to move toward the left and draw with it the rod 5, thus applying the brakes.

he pull upon rod 5 depends of course on the area of the diaphragm and the degree of suction produced invthe casing.

, Release of the brakes is accomplished by reversal of the action described. When the rod 6' moves to the right, the valve 10 will close first and cutofl' communication with the outside air whereupon the valve 14 will ments will become equalized, allowing the brakes'to be released.

Now having describedthe invention and the preferred form of embodiment thereof, it is to'be. understood that the said invention is to be limited, not to the specific details herein set forth but, only by the scope of the claim which follows.

We claim I Brake a plying means comprising a closed cylindrical casing, a diaphragm dividing said easing into two com artments and havingfixed to one side an spaced therefrom a spider, a rod secured to said spider and extendin through one of said compartments and loose y through the adjacent casing wall, said rod being enclosed in a flexible sleeve fixed air-tight to said spider and around the opening in said wall whereby to seal said zompartment, a passage-way from within said ider into said sleeve,a second spideron t e other side of said diaphragm, and in her being provided with a stem of such length as to open one of said valves when the other is seated, spring means adapted to seat said valve to close the first mentioned passage, means for moving the second mentioned rod and the spider attached thee to, means connected to said last mentioned spider to move said diaphragm whereby to seat the valve in the opening therein and open the said passageway normally closed by the other portion of said valve and means.

ada ted to connect the chamber thru which sai second rod passes to an exhaust means.

' DORSEY G. DUTY.

ROY P. SKERRITT.

alignment withthe first, said spiders being movable with respect to eachother, a rod fixed to said second spider and extendin through said other compartment an through its ,ad'acent casing wall in alignment with the first mentioned rod, a flexible sleeve around said second rod and fixed airtight to said'se'cond spider and around the Opening through which said extends whereby to seal said compartment, an opening throu h. said diaphragm within said spider, a ouble valve member adapted to close said opening and also to close the first mentioned passage, said double valve mem- 

